Developing countries, as a group, are the ones most threatened by the hydrological impacts of global warming, even though they are not its primary cause. Impacts are felt through the two principal mechanisms of higher temperatures and altered precipitation patterns. These two effects combine to produce melting mountain glaciers and snowpacks, altered flow patterns in streams and rivers, higher evaporation rates, more extreme precipitation patterns, and rising sea levels, among other things. Human populations will feel these effects in differing ways in different regions. Although some effects will be positive, at least in the short term, the primary impacts in most developing countries will be negative; harming livelihood activities (including crop agriculture, livestock raising, and fishing); reducing domestic water supplies; subjecting larger numbers of people to riverine and coastal flooding and landslides; and altering ecosystem habitats.
